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A series of blends of polyamide 6 (PA-6) (nylon-6) and a copoly(ether-ester) (HYTREL) were prepared by the melt-mixing method using a twin-screw extruder. The HYTREL content was varied from 0% to 25% by weight of the blends. Thermal and rheological studies on the blends using differential scanning calorimetry, dynamic mechanical analysis (DMA) and capillary rheometer showed that the blends are semi-compatible in nature. A two-phase globular morphology of the blends was established by scanning electron microscope (SEM) analysis. The matrix ligament thickness (interparticle distance) in each blend composition was measured from SEM images and compared with those calculated using Wu's equation. The impact strength of the blends as measured by the Izod impact test was found to be substantially improved as a result of the incorporation of HYTREL. The toughness determined by loss area calculation from the DMA spectrum showed similar trends. The toughness was found to be optimal in a blend having 15 wt.% HYTREL with an average dispersed particle size of around 450 nm. The yield stress of the blend decreased in comparison to PA-6 on addition of HYTREL, while the thermal stability of PA-6 remained unaffected. [ABSTRACT FROM AUTHOR]

To determine the thermal kinetic triplets and elucidate the reaction mechanism of thin intumescent fire-retardant coatings (IFR) of steel structures, one efficient combined kinetic approach was implemented in this study. Thermogravimetric experiments were conducted in air atmosphere at four heating rates, and the whole IFR thermal degradation process was divided into two stages. The average activation energy values derived by model-free methods were 78.9 kJ/mol and 175.16 kJ/mol for Stage I (0<α < 0.2) and Stage II (0.2<α < 0.9), respectively. Furthermore, the linear Coats-Redfern (CR) and non-linear Masterplots models were applied to identify the possible reaction mechanism. It was found that the F3/2 mechanistic model was better suited to the main thermal degradation process. Then model reconstruction based on the F3/2 mechanism model was performed. The results showed that the reconstructed model had a strict linear relationship in the independence analysis and KCE analysis, along with a good agreement between the theoretical and experimental results. The current study provided new insights into the systematic thermal degradation mechanism of IFR, and the proposed kinetic model would be helpful for the thermal protection prediction for steel structure during fire. [ABSTRACT FROM AUTHOR]

Scrimber is processed by laminating wood fiber mats impregnated with phenolic resin under hot pressing. One of its essential components is phenolic resin. In this study, the effect of phenolic resin content on the structural, water-resistant, mechanical, and thermal properties of pinewood scrimbers was investigated. Results showed that phenolic resin facilitated the collapse of cell walls at low pressure during lamination, and higher resin content markedly reduced cell wall cracking. The cellulose I structure of pinewood remained intact, whereas its crystallinity decreased as resin content increased. Moreover, the resin significantly improved water resistance and dimensional stability; an increase in resin content led to a more pronounced improvement. The water absorption in 35 h at a resin content of 15 wt.% was approximately 1/10 of that at 9 wt.%. Scrimbers with a resin content of 9 wt.% exhibited a 50% increase in modulus of rupture (MOR) and a more than 1.4-fold increase in modulus of elasticity (MOE) relative to that of solid pine wood. As the resin content increased, MOR remained stable, MOE slightly decreased, and shearing strength increased. In addition, phenolic resin promoted the thermal degradation of scrimbers, and the higher resin content in the scrimber led to better thermal degradation. [ABSTRACT FROM AUTHOR]

Polymer gel has been accepted as a useful tool for solving many sealing operations such as fluid loss control, enhanced oil recovery, water and gas shutoff, wellbore integrity, and well stimulation in the upstream of petroleum industry. In a previous study, we used acrylamide (AM), N,N'-Methylenebisacrylamide (MBA), xanthan (XC) and chromium acetate (Cr3+) to obtain ultra-high strength gel (USGel). Some interesting phenomena, such as the more than 10 times increase in gel strength by 0.05% Cr3+ and the counter-conventional decrease in gel strength by inorganic particles such as layered silicate materials (LSM), silicon dioxide nanoparticles (SiO2) and laponite (RDS), have not been well explained. In this paper, the gelation kinetics and mechanism of USGel were investigated mainly by bottle, DSC, infrared spectroscopy, and environmental scanning electron microscopy (ESEM) experiments, which explained that Cr3+ significantly increased the gel strength of USGel, while inorganic particles had a negative effect on the gel strength. The experimental results showed that Cr3+ preferentially cross-linked AM and XC than MBA, and the gelation rates of Cr3+-XC and Cr3+-AM were 107% and 92.9% faster than AM-MBA, respectively. It is speculated that the triple network structure and physical entanglement formed by AM-MBA, XC-Cr3+, and AM-Cr3+ are the main reasons for significant improvement of gel strength by Cr3+, and the cross-linking competition between LSM and Cr3+ and reduction of entanglement number are the main reasons for the significant reduction of gel strength by LSM. This paper provides new insights into the preparation of ultra-high strength gels and the usage of inorganic particles. [ABSTRACT FROM AUTHOR]

Thermal decomposition behavior and kinetics of four kinds of Chinese heritage architectural wood were investigated by thermogravimetric analysis. Experiments were carried out in air atmosphere up to 600°C. The thermal degradation process of historical wood involved a two-step reaction kinetics, consisting of a low-temperature stage (230–370°C) and a high-temperature stage (370–485°C). Distributed activation energies determined using Coats-Redfern method and the first-order model (O1) have optimum fitness compared with nth-order model functions. The lignocellulosic components of white pine and red pine have similar thermal stability, spruce has the slowest combustion rate or best thermal stability, and the reactivity of charcoal and lignin with oxygen of nanmu was higher than that of other three types of historical wood. The activation energy of four historical wood species is lower than that of most fresh wood and varied from 75.10 to 83.39 kJ/mol in the first stage and 10.75 to 15.97 kJ/mol in the second stage. [ABSTRACT FROM AUTHOR]

In recent years, numerous research studies have been performed in the field of pyrolysis and thermochemical biomass transformation into biofuels, i.e. bio oil, biochar and biogas. Additionally, pyrolysis is an efficient and effective conversion technology as compared to other thermochemical technologies due to various socioeconomic benefits. Biomass, and its composition, plays an ultimate role in the determination of pyrolysis products and is an ecofriendly or promising alternative source of renewable energy. This review paper attempts to suggest specific criteria for biomass selection for the pyrolysis process to obtain maximum yield of biooil, biochar and biogas. Lignin, cellulose and hemicellulose are the key constituents present in varying biomass which greatly affect the products of pyrolysis. This review paper summarises biomass resources, types, the composition of biomass, preliminary tests and physical and chemical characteristics for suitable selection of biomass for pyrolysis. [ABSTRACT FROM AUTHOR]

The influential effects of thermal treatment on material density, hardness, colour and microstructure of three commercially available woods in South Asia are evaluated. Wood specimens are isochronally annealed 120 min at different temperatures up to 250°C and isothermally annealed at 100°C, 150°C and 225°C up to 480 min under atmospheric pressure. Heat treatments cause density loss, hardness loss, darkening and microstructure frailer of woods, as the maximum temperature was increased. However, thermal treatment up to the temperature around 150°C shows lower values for the case of density, higher values for hardness and no remarkable changes in colour of wood specimens. Higher temperature treated samples are found to recover through absorbing water (moisture); however, chemically bonded water and thermally lost substances cannot be recovered. The diffuse reflectances of all the wooden samples decrease with the increase of annealing temperature, especially at colour band of higher wave length. The negative effects of the high-temperature thermal treatment on the properties of all the woods are observed due to removal of the free, loosely and chemically bonded water of woods, along with higher thermal degradation of cellulose, hemicelluloses and lignin. The SEM microstructures of the wood samples also comply with the present investigation showing the damage structure of fibres and pores. [ABSTRACT FROM AUTHOR]

Herein, piperazine phosphoramide derivatives (PPDO) and titanium carbide modified by hexadecyl trimethyl ammonium bromide (c-Ti3C2) were blended with epoxy resin (EP) to fabricate EP/c-Ti3C2/PPDO nanocomposites. According to thermogravimetric analyzer (TGA) results and pyrolysis kinetic analysis, EP/c-Ti3C2/PPDO nanocomposites can improve the thermal stability and the activation energy of EP. Furthermore, thermal degradation mechanism of EP and its nanocomposites with conversion between 0.55 and 0.99 conforms to the F3 model. With 1 wt% c-Ti3C2 and 3 wt% PPDO incorporated, the LOI value of EP/c-Ti3C2-1/PPDO-3 can reach up to 32% while achieves V-0 rating in the UL-94 test. Based on the cone calorimeter results, the peak heat release rate of EP/c-Ti3C2-1/PPDO-3 reduced by 40.1%. More continuous and dense phosphorus-rich char residues were produced for EP/c-Ti3C2-1/PPDO-3 nanocomposites, which can act as a physical barrier to hinder the heat transfer, protect the underlying polymers from further decomposition and isolate the diffusion of combustible gases. The synergistic effect between c-Ti3C2 and PPDO in catalytic carbonization obviously accounts for the improved flame retardant performance. This work provides an insight into the flame retardant mechanism and the thermal degradation mechanism of c-Ti3C2 and PPDO on EP, showing a promising application potential of c-Ti3C2 and PPDO in enhancing the thermal stability and flame retardancy of EP. [ABSTRACT FROM AUTHOR]

The improvement of flame retardants in controlling polymer combustion behavior is mainly based on their effect on the polymer thermal degradation behavior. In this article, the Kissinger method and Flynn-Wall-Ozawa method were used to study the thermal degradation behavior of alginate (Alg)/graphene composite fibers. The results of activation energy calculated by the two methods were very consistent. The addition of a graphene-based flame retardant (GO-DOPO-V, where GO represents graphene oxide, DOPO represents 9,10-dihydro-9-oxy-10-phosphoxanthine-10-oxide and V represents vinyltrimethoxysilane) increased the thermal degradation activation energy of the Alg composite fiber and enhanced the thermal stability and flame retardancy of the fiber. The Flynn-Wall-Ozawa method further revealed that the addition of GO-DOPO-V induced a condensation reaction of the polymer at the early degradation stage of the Alg composite fibers, leading to a decrease in the thermal degradation activation energy. At the final stage of the thermal degradation, with the formation of a char layer, the thermal degradation and activation energy of the Alg composite fibers were improved under the action of GO-DOPO-V, and the flame retardancy of the Alg composite fibers was enhanced. [ABSTRACT FROM AUTHOR]

Food and agricultural industries contribute a massive amount of organic waste, rich in bioactive molecules, including various proteins, fatty acids, carbohydrates, enzymes and many other biomolecules. With increasing emphasis on waste reduction, bio-based product development, and the provision of nutrition for all, these resources are being exploited for nutraceutical extraction, nutrient recovery for food fortification, and bioplastic production, among many other valorized applications. Transportation and storage are essential parts of all these enterprises, for which drying can be beneficial through reduction of cost of transportation and increased shelf-life. However, the processing and drying of these materials can be challenging, due to the inherent physicochemical properties of these biomaterials and the nonexistence of an industrial setup for handling waste. Complicacy of the concepts and technologies for applying these materials can also vary in regions around the world, depending on local agricultural and food industry practices. This manuscript will focus on these issues and discuss some of the techniques to deal with them in the current scenario, along with possible future perspectives relevant to the food industries. [ABSTRACT FROM AUTHOR]

Cellulose, consisting of β-anhydro-d-glucose units, is a natural, biodegradable, and versatile biopolymer with several applications in food and non-food systems. Cellulose is probably the most abundant biopolymer in the biosphere and is synthesized by multiple living organisms, ranging from some bacterial species to higher plants. Cellulose recovery was initially done from forest wood mainly. Other sources, including agro-industrial by-products, such as, fruit peels, husks, revealed to be potential reservoirs of cellulose. Recycling agro-industrial waste by recovering cellulose is an ideal strategy to mitigate the impact of food waste from agro-industrial activities. Moreover, the tremendous potential of cellulose nanomaterials has fueled researchers' interest in developing environmentally friendly extraction techniques. The present review paper focuses on the recovery of nanocellulose from different agro-industrial by-products and reports the advantages of the extraction technique used, such as, the use of deep eutectic solvents, ultrasound, steam explosion, mild acids, reduced effluents, amongst others. The importance of characterizing the physico-chemical properties of nanocellulose from different sources is also discussed. It is expected that scientific findings presented in this paper will highlight the potential of agro-industrial wastes as cellulose reservoirs and the importance of physico-chemical characterization of nanocellulose. [ABSTRACT FROM AUTHOR]

Despite the wealth of physical and chemical information available about wood torrefaction and pyrolysis, very few studies to date have focused on the transition between these two processes. It has been experimentally determined, however, that torrefaction and pyrolysis lead to very different products, indicating a change in their degradation chemistry. There exists, therefore, a need to investigate this transition between torrefaction and pyrolysis from a chemical perspective, very useful for the development of kinetic models. This study focuses on investigating thermogravimetric analysis, shrinkage, flexural strength, total weight loss, of two common industrial European wood species treated at temperatures ranging from 250°C to 400°C. A comparison reveals an obvious change in the degradation of cellulose as a function of treatment temperature that can be correlated with the yield of the main thermal treatment products, such as acetic acid, furfural, CO, H2, etc. At temperatures higher than 350°C, all wood components are extensively degraded. In conclusion, this study indicates a deep modification during the transition between torrefaction and pyrolysis. The results obtained in this study help establish specific temperature ranges, based on wood component degradation, that can be used in the refinement of kinetic models for wood thermal treatment. It is envisioned that, due to the sudden change in behavior at temperatures covering a range between torrefaction and soft pyrolysis, an adequate model with distinct stages is required. Ultimately, this study aims at defining, based on TGA, DTG, mechanical testing, color/appearance, and dimensional change results, the appropriate temperature ranges to be used in the refinement of unique kinetic models that contemplate the degradation of wood components. [ABSTRACT FROM AUTHOR]

The thermal degradation of the wood and bark of the Black locust (Robinia pseudoacacia L.) and Scots pine (Pinus sylvestris L.) cultivated as monocultures in marginal lands of Ukraine has been investigated using thermogravimetric methods of differential thermal analysis. The activation energy of the trees' bark and wood destruction processes were calculated for each temperature range. Comparison of DTA curves showed that the thermal effect of oxidative destruction of the Black locust bark as a whole is greater than that of wood, which correlates with a decrease in the activation energy. [ABSTRACT FROM AUTHOR]

The effects of acid hydrolysis parameters (acid type, acid concentration, reaction time, and temperature) on the properties of nanocellulose (NC) extracted from almond shells were investigated. The highest percentage yield of NC obtained from each type of acid was 71.8% using 25% w/v sulfuric acid at 50°C for 60 min, followed by 71.1% with 50% w/v perchloric acid at 35°C for 15 min, and finally 67% with 50% w/v methane sulfonic acid at 25°C for 10 min. The hydrolysis treatment using sulfuric and perchloric acids greatly affect the NC particle size and length. The extracted NCs show different thermal degradation profiles due to the difference in the crystallinity index and types of acid used. Hydrolysis with strong acids (sulfuric and perchloric acids) produce NC with lower crystallinity due to the degradation of both amorphous and crystalline regions in the cellulose. Furthermore, BET analysis revealed the NCs from the hydrolysis using sulfuric acid possesses the highest surface area, desorption/adsorption pore diameter, desorption, and adsorption cumulative pore volume compared to other acids. [ABSTRACT FROM AUTHOR]

The structural porosity weakness of a natural flax fiber-layered polymer laminate was reduced by the spatial rearrangement of natural almond shell filler occupying preferentially porous sites between the stacking layers, improving the properties of the polymer laminate. The present work investigates the mechanical, thermal, and free vibrational behavior of composites, including surface modification and the effect of almond shell filler loading in the flax fiber intertwined composites. Alkaline treatment of natural flax fiber and almond shell filler effectively reduced the hydrophilic contents of hemicellulose, lignin, and wax without altering the cellulose nature, as confirmed by FTIR analysis. Tensile strength was 35% higher for the alkaline-treated 10% almond shell-filled composite than the untreated filler composite. However, the tensile strength decreased beyond 10% of filler loading because of the poor dispersion of fillers in the matrix. As evident in the 10% filled almond shell composite, due to stronger interaction, polymer-mixed almond fillers act as a thermal insulating layer between the flax stacks, increasing thermal stability. Alkali treatment with an almond shell of 10 wt% filled flax fiber composite exhibited a higher natural frequency (185 Hz) and damping value (0.042) due to total internal dissipation of dynamic forces. [ABSTRACT FROM AUTHOR]

According to the SEM results of BOVIFs, it was observed that the fiber diameter of BOVIFs varies along the fiber longitude. Effect of fiber surface treatment and fiber loading on the properties of bagasse fiber-reinforced unsaturated polyester composites. BOVIFs consist of cellulose (47.8 wt.%) and lignin (13.4 wt.%). In literature, it is reported that plant-based fibers consist of helically wound cellulose micro fibrils, bound together by an amorphous lignin matrix. SEM images show that the fiber diameter of BOVIFs varies along the fiber and BOVIFs have a rough surface structure. [Extracted from the article]

In the present work, physico-mechanical, chemical composition, and thermal properties of cellulosic fiber extracted from the stem of Hibiscus vitifolius plant have been investigated. The wide characterization was conducted on the Hibiscus vitifolius (HV) fibers and the results proved their potentials for composite applications. Characterization tests on HV fibers confirmed the chemical constituents such as cellulose (75.09 wt. %), lignin (10.42 wt. %), hemicelluloses (13.34 wt. %), wax (0.17 wt. %), ash (0.94 wt. %) and moisture content (11.31 wt. %). The density of HVFs was found to be 1530 kg/m3. X-ray diffraction analysis of HVFs revealed 67.07% crystallinity index and 2.09 nm crystallite size. Tensile strength and percentage of elongation at failure exhibited by HVFs examined through single fiber tensile test was found to be 224.32–716.70 MPa and 3.99–8.77%. Thermo gravimetric analysis revealed thermal stability of HVFs up to 260°C with kinetic activation energy of 126.86 kJ/mol. Cellulose with high crystallinity index, lower wax content, good tensile resistance and better thermal behavior make HV fibers more suitable for composite manufacturing. The morphology of fiber surface studied through SEM images revealed the presence of more roughness at the outer surface which can improve the fiber-matrix bonding during composites preparation. [ABSTRACT FROM AUTHOR]

Application of regenerated thermodynamic inhibitor (THI) is a cost-effective way of hydrate inhibition in oil industries. There have been literature reports for application of regenerated THI monoethylene glycol (MEG) in order to keep the process economical and also to avoid releasing the used MEG to the environment in order to reduce its impact. In our previous studies, thermodynamic gas hydrate equilibrium curves were established for pure propylene glycol. So, in continuation to previous work, thermal degradation of propylene glycol is studied in this research to be applicable for gas hydrate inhibition as regenerated product. A laboratory batch distillation setup is utilized for conducting thermal degradation of propylene glycol (40 and 80 wt%). Degraded products were collected at different time intervals to identify generated organic acids. Major degradation product observed was lactic acid and other generated acids include formic, acetic and pyruvic acid. Results showed increase of degradation product concentration with increasing retention time and higher propylene glycol concentration. The degradation characteristics studied in the research work will be helpful to identify the parameters affecting the degraded propylene glycol efficiency to be tested as gas hydrate inhibitor in our future research work. [ABSTRACT FROM AUTHOR]

In this work, pyrolysis experiments were carried out in a stainless steel semi-batch reactor to produce a diesel-like fuel from waste polypropylene (PP). Aiming to maximize the liquid oil yield, the optimal reactor operating conditions (e. g. heating rate, batch time, degradation temperature, and N2 flow rate) was obtained by the investigation of the thermal behavior of the waste PP using Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA). The waste PP pyrolysis oil was successfully purified by adsorption onto activated carbon, resulting in a colorant removal percentage of 49.56% as well as in the removal of the particle matter. The functional groups of purified waste PP pyrolysis oil (PWPO) and the Brazilian commercial S-10 diesel fuel were obtained and compared using Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography Coupled to Mass Spectrometry (GC-MS). According to the experimental results, the proposed thermal pyrolysis process has shown a very high liquid oil yield of about 94 wt%, and fuel heavy and light hydrocarbons were identified in PWPO. It was observed that PWPO has physico-chemistry properties similar to those of commercial S-10 diesel fuel, enhancing the high lower heating value (LHV) of about 43.06 MJ/kg. The work findings pointed out the synthetic diesel-like fuel as a promising alternative for cycle diesel engines, dropping the use of fossil fuels without reducing energy efficiency. [ABSTRACT FROM AUTHOR]

In this study, the effect of thermal exposure on the mechanical, physicochemical, microstructural and self-cleaning properties of photocatalytic cement mortars was investigated. 1%, 2%, 3% and 4% of the ordinary Portland cement weight was replaced with nano-TiO2 particles. Mortars were heated at a rate of 2 °C/min to 200 °C, 400 °C, 500 °C, 600 °C, 700 °C and 800 °C. Compressive and flexural strengths, mass, water porosity, ultrasonic pulse velocity, optical microscopy, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis tests were conducted before and after heating the mortars. The experimental results showed that nano-TiO2 particles have a significant influence on the residual properties of the mortars. The addition of TiO2 increased the resistance of the mortars to thermal deteriorations and preserved the residual mechanical, physicochemical and microstructural properties of the mortars. Additionally, for the first time, the influence of thermal exposure on the photocatalytic performance of cement composites was evaluated in this study by evaluating the degradation of rhodamine B. The photocatalytic performance was unaffected up to 400 °C, however, further heating deteriorated the photocatalytic performance of cement mortars. [ABSTRACT FROM AUTHOR]

The effect of graphene modified with a phosphorus and silicon-containing compound (GO-DOPO-V) on the flame retardancy and thermal stability of epoxy resin (EP) was studied by cone calorimetry and thermogravimetric analysis (TGA) in nitrogen. After incorporation of 2 wt% GO-DOPO-V into EP, maximum decreases of 28.8% in peak heat release rate (pHRR) and 15.6% in total heat release (THR) were achieved compared to that of pure EP. It was shown that GO-DOPO-V significantly promoted the formation of an EP tight char layer and the char residue of EP/GO-DOPO-V composite at 600 °C was 13.39 wt%, which was almost twice that of pure EP. Furthermore, the non-isothermal degradation behavior of EP/GO-DOPO-V composites were investigated also in a nitrogen atmosphere. It was found that the addition of GO-DOPO-V changed the degradation behavior of EP composites in the early and middle stages. Both the Kissinger and Flynn–Wall–Ozawa methods revealed that the addition of GO-DOPO-V increased the thermal degradation activation energy of EP, and improved the flame retardancy of the polymer matrix. [ABSTRACT FROM AUTHOR]

Thermal stability and kinetics of thermolysis of postconsumer milk containers made of high-density polyethylene (PC-HDPE) and filament rods extruded from them (HDPE-F) were examined by thermogravimetric analysis (TGA) with six linear temperature programs under a stream of nitrogen. The total weightloss of each sample took place in a one-step decomposition to volatiles at the heating rates, β = 1, 10, 25, 50, 70, and 100 Kmin-1. The values of initial decomposition temperature, the temperature at the maximum thermal degradation rate, and the maximum rate of decomposition were increased by increasing the heating rate as was the expectation. The isoconversional method was used to evaluate the fundamental kinetic parameters, the activation energy barrier (Ea), the Arrhenius pre-exponential factor (A), and the mechanism of the reaction, f(α). The values of Ea were independent of the model and heating rate, as was expected. However, the values of A depended on the model and the extent of reaction (α). The values of the Ea of PC-HDPE initiated at 171 kJ/mol at α = 0.05 and it increased to 207 kJ/mole at α = 0.95. The values of Ea of the HDPE-F rod were relatively constant for all α values, being 227 ± 3 kJ/mol. It was justified by the absence of easily volatilized substances in the HDPE-F. Knowledge of the thermal stability and decomposition kinetics of the starting materials (PC-HDPE) and the product (HDPE-F) is important in the context of thermochemical conversion processes aimed at the use of PC-HDPE as raw materials for recycling, upcycling, and down-cycling for objects used under room conditions. [ABSTRACT FROM AUTHOR]

The fire retardancy of a thiol-ene (trimethylolpropane tris(3-mercaptopropionate)-pentaerythritol allyl ether, PTE) polymer was enhanced by the incorporation of fire retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The cone calorimetry results showed that, compared with pure PTE, the peak heat release rate (PHRR) and total heat release (THR) of the PTE composite at 5 wt% DOPO loading were reduced by 40.9% and 21.8%, respectively. The Kissinger and Flynn-Wall-Ozawa methods were both employed to analyze the TGA data of the PTE and fire-retardant PTE (FRTE) composites. It was clearly observed that the activation energies of pure PTE and the FRTE composites calculated using the two methods followed the same trend; the activation energies of the fire retardant PTE were lower than those of pure PTE, which we attribute to the fire retardant DOPO improving the thermal stability and fire retardancy of PTE. [ABSTRACT FROM AUTHOR]

In this study, the bending properties and damage accumulation behavior of carbon-fiber-reinforced thermoplastics (CFRTP) were investigated to understand the effect of heat treatment on crystallization. Further, three-point bending tests using the acoustic emission technique were performed. Results indicated that a short period of heat treatment increased the CFRTP bending strength; however, for an excessively long heat treatment (30 h), the CFRTP bending strength decreased. To understand cause for the increase and decrement in the bending strength via heat treatment, surface observations using a laser microscope and thermal property measurement using differential scanning calorimetry were performed. Results showed that the 30-h heat-treated specimens exhibited fiber-matrix debonding before bending tests because of matrix shrinkage caused by crystallization and thermal degradation. Fourier transform infrared spectroscopy analysis revealed that the cause of deterioration was oxidation, and oxidation cleaved the molecular chains and embrittled the matrix. Consequently, we could control the bending properties by crystallization, and the relationship between crystallization and strength agreed with the formulated constitutive equation. However, we must address the thermal degradation when the materials are subjected to heat treatment. [ABSTRACT FROM AUTHOR]

Agriculture and forest residues have a large energy potential and there are eligible to become sustainable promising energy resources in future. Present study deals with the analysis of thermo-physical properties, Fourier transform infrared spectroscopy (FTIR), and kinetics of corncob and eucalypts. The pyrolysis, Combustion characteristics and Kinetic deconvolution of biomass have been evaluated by thermo-gravimetric analyser from atmospheric temperature to 1100°C at a heating rate of 10°C/min. The kinetic analysis of biomass was determined by Flynn-Wall-Ozawa (FWO) methods. From the results, the average activation energies of corncob and eucalyptus were found as 91.29 and 77.21 kJ/mol respectively. The results showed that corncob was sensitive to rate of heating due to lower lignin content. [ABSTRACT FROM AUTHOR]

Deterioration of polymer materials can cause breakdown of various automobile parts during their life cycles, which is a threat to the safety of occupants. In the research described here various thermal stabilizers were incorporated into polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends, often used in automotive parts, to investigate the thermal degradation of PC/ABS as a function of mixing rate and mixing time and as a function of stabilizer type and content. A phenolic stabilizer, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (S1) and two kinds of phosphite stabilizers, tris-(2,4-di-tert-butyl-phenyl phosphite) (S2) and bis(2,4-dicumylphenyl) pentaerythritol diphosphite (S3) were used. Thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) results showed that high mixing rates, over 2000 rpm, caused high shear heating, which brought about thermal degradation of the polymer blends. The S3 better prevented thermal degradation of the PC/ABS blends during high speed processing compared to the other stabilizers. Characterization of the mechanical properties of the blends prepared at a screw speed of 1000 rpm for 20 sec indicated decreases in elongation at break from 148% prior to processing to 63% for S1, 108% for S2 and 131% for S3, whereas the tensile strengths showed only slight changes. Scanning electron microscope (SEM) images indicated that the size distribution of the dispersed phase was decreased with increasing screw speed and mixing time. The interfacial tension of the blends decreased with increasing mixing rate, whereas it did not exhibit significant change with increasing mixing time. [ABSTRACT FROM AUTHOR]

Measurement of the antioxidant additives during lubricant thermal degradation is a useful method for providing a quantitative basis to understand the performance of the lubricant. In this study, a synthetic ester-based aviation oil was thermally exposed for a period of 500 h under gas turbine aero engine representative conditions using a lubricant/system interaction simulator (L/SIS) test rig. Physical and chemical changes including kinematic viscosity, total acid number (TAN), and oil chemical composition were monitored during the experiment. The change in oil chemical composition, with a particular focus on antioxidant additives, was examined using gas chromatography–mass spectroscopy (GC-MS) techniques. The results indicate that the identified antioxidants in the lubricant, dioctyl diphenylamine (DODPA) and phenyl-α-naphthylamine (α-NPA), were consumed during the degradation process of the oil, with DODPA having a slightly higher depletion rate. Posttest analysis of the stressed samples showed an increase in viscosity and TAN of the lubricant oil in the course of the thermal exposure. Furthermore, the reaction of DODPA and α-NPA in an oil thermally degrading environment was compared using density functional theory (DFT). The calculations indicate a lower energy barrier for the reaction of oil with DODPA. [ABSTRACT FROM AUTHOR]

In this investigation the flame-retardant effect of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) on an epoxy resin (EP) was studied. The results showed that the peak of heat release rate (PHRR) and total heat release (THR) of EP/DOPO (FREP) with 5phr DOPO during cone calorimeter measurements were only 67.4% and 75.3% of those of pure EP, respectively. The thermal degradation behavior of FREP was analyzed by the Kissinger and Flynn-Wall-Ozawa methods, both of which indicated that the activation energy of the FREP thermal degradation was lower than that of pure EP. This was attributed to the addition of DOPO into the resin, which promoted the thermal degradation of the EP composite. [ABSTRACT FROM AUTHOR]

The performance of 10 natural yellow colourants at different concentrations (0.001–0.3% w/v) was investigated in a model beverage system at various pH levels (3.5, 5.5 and 7.5) containing 10% w/v of sucrose, with or without ethanol (15% v/v) to simulate both alcoholic and non-alcoholic lemon-like beverages. Thus, the incidence of pH, ethanol and colourant concentration on spectral properties as well as turbidity were evaluated. The λmax was found to be independent from concentration in the tested range (0.001– 0.3% w/v), whereas the specific absorbance at λmax increased linearly. Moreover, the absorption spectrum and λmax of yellow pigments were found to be independent of pH and ethanol. Gardenia, safflower, and curcumin had the highest colour intensity and the lowest turbidity level. Heat and light stability were studied for these as well. Safflower was found to be the most stable colourant against heat (25, 40, 60, 80°C) and light (550 W/m2, 30°C). [ABSTRACT FROM AUTHOR]

In this article, we have shown an easy, one-step, protein-directed approach for the synthesis of water-soluble and functional graphene using ovalbumin. The obtained ovalbumin functionalized graphene was characterized by UV–visible spectroscopy, X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. Atomic force microscopy was used to check the attachment/functionalization of ovalbumin on grapheme sheets. It was shown that the functionalization of ovalbumin on grapheme sheets makes the protein more thermally stable compare to free ovalbumin, which has been shown by using sodium dodecyl sulfate polyacrylamide gel electrophoresis. [ABSTRACT FROM AUTHOR]

Commercial fluororubber SKF 32, fluoroplastic F-32L, fluoroelastomer Kel-F, fluoroplastic FK 800 (labeled as SKF 32, F-32L, Kel-F and FK 800) and an in-house prepared poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM) copolymer were investigated in terms of their thermal degradation kinetics, reaction models and corresponding thermodynamic parameters. All samples underwent a single step thermal degradation using thermogravimetric analysis (TGA) at different heating rates under nitrogen atmosphere. The kinetic parameters were determined through the Kissinger method and three isoconversional methods; viz. the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink. The activation energies of the SKF 32, F-32L, Kel-F, FK 800 and FKM obtained using the Kissinger method were 206, 200, 185, 221 and 243 kJ mol‒1, respectively. The activation energy values for the degradation obtained using the KAS method were: 180–225 kJ mol−1 for SKF 32, 192–209 kJ mol−1 for F-32L, 163–185 kJ mol−1 for Kel-F, 213–227 kJ mol−1 for FK 800 and 187–269 kJ mol−1 for FKM with the extents of conversion (α) = 0.1–0.9. These values of the activation energies obtained from the KAS method were in good agreement with those obtained using the FWO and Starink methods. In addition, the appropriate degradation reaction models were determined by means of the Coats-Redfern and Criado methods. The thermodynamic parameters, such as activation Gibb free energy, ΔG*, activation enthalpy, ΔH*, and activation entropy, ΔS*, for formation of the activated complexes during the thermal degradation were also determined and discussed. The positive values of the Ea, ΔG*, ΔH*, and ΔS* for SKF 32, F-32L, FK 800 and FKM indicated a non-spontaneous process, while the positive values of the Ea, ΔG* and ΔH*, and negative value of ΔS* for Kel-F meant that the formation of the activated complex was accompanied by a smaller decrease of entropy than for the other polymers. [ABSTRACT FROM AUTHOR]

N-phenylmaleimide (N-PMI) and its precursor, (Z)-4-oxo-4-(phenylamino)but-2-enoic acid, were synthesized from aniline and maleic anhydride. Copolymerization between N-phenylmaleimide and styrene was initiated in micropores and outside surface of porous polyvinyl chloride (PVC) resin suspended in aqueous phase. The modified PVC was characterized with Gel Permeation Chromatography, thermal gravimetric analysis and scanning electron microscopy. The result of high performance liquid chromatography shows that the purity of N-PMI reached 97.3%. Thermal gravimetric analysis indicated that the introduction of N-PMI could clearly affect the thermal degradation behavior of PVC, and when PMI was at 6.25% of the PVC mass, the decomposition temperature T0.5 of modified polymer was increased to 314.2°C. The glass transition temperature of modified polymer was increased from 70°C to 80°C. [ABSTRACT FROM AUTHOR]

In order to synthesize the high temperature solid lubricating film by gas-phase polymerization at 500 °C with two kinds of gasified monomers for use in airplane and rocket engines, the polymerizing activity of terephthaloyl chloride (TPC) and p-phenylenediamine (PPD) at 500 °C and their polymerized product poly-p-phenyleneterephthamide (PPTA) as well as its decomposed solid residues were researched. It was proved by FT-IR and 1HNMR on the solid residues after the 10 min experiment of the both monomers in muffle furnace at 500 °C and PPTA synthesized by conventional method that at 500 °C the polymerization tendency of these monomers should trump their decomposition tendency. The solid residues after the 10 min experiment mainly consisted of polymerized products which would decline as the experimental period increases, while the content of decomposed and carbonized products would raise. FT-IR and elemental analysis revealed a similar structure of the solid residues after the both monomers or PPTA calcined for 60 min at 500 °C, which further demonstrated the polymerized products would degrade, decompose and carbonize after the prophase polymerization. Finally, effects of experimental temperature and monomers molar ratio on amounts and structures of the solid residues were discussed to propose preliminary mechanisms of polymerization and decomposition. [ABSTRACT FROM AUTHOR]

A compatibility of energetic compound with polymeric matrices is of prime importance in the pre-formulation stage for developing of new energetic composite formulations. In the present work, the compatibility of octahydro-l,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) with polyether (PET) polyol (trade name SP-755)-based polyurethanes (PUs) containing different curatives such as 4,4ʹmethylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), 2,2,4-trimethylhexamethylene diisocyanate (TMDI), and toluene diisocyanate (TDI) has been studied by using a differential scanning calorimetry method. The PET-based PUs were prepared by polymerization between PET polyol and different curatives, then these PUs were further mixed with HMX to study the compatibility and kinetic parameters. Results show that the compatibility and thermal stability are significantly influenced by the different curatives, and suggested thermals stability by thermal data follow the order for a mixture of HMX/SP-755/MDI > HMX/SP-755/TDI > HMX/SP-755/IPDI > HMX/SP-755/TMDI. The thermal degradation kinetics has also been investigated through non-isothermal conditions using the Kissinger and the isoconversional ASTM E689 kinetic methods. The finding shows that there was a significant variation in the apparent activation energy for a mixture of HMX/SP-755/MDI, HMX/SP-755/IPDI, HMX/SP-755/TMDI, and HMX/SP-755/TDI, which were 365.8, 257.7, 134.9, and 241.1 kJ mol−1, respectively. The apparent activation energies obtained from the Kissinger method at maximum peak temperature are in reasonable agreement and consistent with isoconversional ASTM E689 kinetic method. [ABSTRACT FROM AUTHOR]

Cornelian cherry fruits are rich in health-related compounds. In the present study, the ultrasound-assisted extraction was used to maximize the recovery of anthocyanins and phenolic compounds from cornelian cherry. The optimal extraction conditions were determined and the influence of independent variables was checked through response surface methodology. The maximum recovery of anthocyanin and total phenolic compounds was obtained after 40 min at 30°C, when performing the extraction with aqueous ethanol of 80% and 60%, respectively. The major anthocyanins identified through HPLC were cyanidin-3-rutinoside and cyanidin-3-glucoside. The thermal degradation kinetic study revealed that up to 120°C, the anthocyanins from cornelian cherry were thermo-resistant, whereas at more severe temperatures were easily degraded. The kinetics of the heat-induced changes in total monomeric anthocyanins followed a first-order kinetic model, allowing to predict the thermal degradation parameters. [ABSTRACT FROM AUTHOR]

In this work, anthocyanin of rose residue was microencapsulated, using spray-drying (1:1 (w/w) of GA to MD, the inlet air temperature was170°C, the drying airflow rate was 5.0 m3/min, feed rate was 0.36 L/h) and freeze-drying (processing 48 h at −52°C, vacuum degree was 0.45 mbar) with gum arabic and maltodextrin as external materials. The total phenolic content (TPC), anthocyanin content (ACN), antioxidant activity, moisture content, water activity (Aw), solubility, hygroscopicity, colorimetric property, particle micromorphology and size distribution of the microencapsulated anthocyanin were measured. Thermal degradation kinetic and thermodynamic parameters of ACN extracts and microcapsules in the accelerated model were determined. The spray-dried powder (SDP) presented a spherical shape while the freeze-dried powders (FDP) were in indefinite and laminated structures with more homogeneous distribution. After microencapsulation, the retention rate of TPC and ACN was 86.00% and 75.85% for SDP, 91.44% and 95.12% for FDP, respectively. Both of spray-dried and freeze-dried strategy provided efficient preservation for rose residues, enabling them to have lower moisture content, water activity, significantly higher solubility (P <.05) compared with the rose anthocyanin extracts (RAE), and have high-fidelity color that was similar to RAE. Meanwhile, the antioxidant activity of the microcapsules decreased with the deteriorating of bioactive compounds. In the degradation kinetic study of anthocyanin at the temperature 70, 80, 90°C, both FDP and SDP had longer half-life duration, lower absolute value of activation entropy, and better effect of freeze-drying embedding method compared to RAE. Therefore, microencapsulation, especially by freeze-drying method, could efficiently enhance the stability of anthocyanin in rose residue during thermal processing and storage, and thus greatly facilitate the utilization of by-product of rose essential oil. Abbreviations: RAE: rose anthocyanin extracts; GA: gum arabic; MD: maltodextrin; SDP: spray-dried powders; FDP: freeze-dried powders; TPC: total phenolic content; ACN: anthocyanin content [ABSTRACT FROM AUTHOR]

An advanced, heat-resistant fluoroether rubber (FM-20) was subjected to dynamic thermogravimetric analysis (TGA) in the air atmosphere. The results suggested that its thermal degradation process can be divided into two parts. As the heating rate increased, the initial decomposition temperature and degradation temperature would move to higher ranges. The apparent activation energy of thermal decomposition, calculated by the Kissinger, Friedman and Flynn-Wall-Ozawa methods were 209, 240, and 211kJ/mol, respectively. Furthermore, the probable thermal degradation mechanism was also analyzed by the Coats-Redfern method. As a result, the most reasonable thermal degradation mechanism of FM-20 was g (α) = α3/2 [ABSTRACT FROM AUTHOR]

The reactive polyurethane hot melt adhesive (HMPUR) was synthesized via bulk polymerization of poly(butyleneglycol adipate) (PBA), poly(ethylene orthophthalate) (PEO), poly(tetrahydrofurandiol) (PTMEG), 4,4′-methylene diphenyl diisocyanate (MDI) and pentaerythritol diacrylate (PEDA). Its thermal degradation was studied by thermogravimetry (TG) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In helium atmosphere, the sample was pyrolyzed at three characteristic temperatures of 280, 450 and 600 °C according to the results of TG analysis. More than 20 characteristic volatile pyrolytic products were identified by on-line MS. The pyrolysis reaction types of HMPUR were proposed and verified through the analysis of pyrolytic products. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) nanocomposites containing 3%, 5% and 7% zeolite used in the present research study were prepared by solution casting. The PLA nanocomposites were structurally characterized by Scanning Electron Microscopy and Fourier-transform infrared spectroscopy. The effects of the gamma radiation at the absorbed doses of 10, 15 and 20 kGy on the structures and thermal properties of the nanocomposites were investigated in a tetrahydrofuran solvent. Thermodecomposition tests and analyses were carried within 30-500°C range at the rate of 10°C min−1 by thermogravimetric analysis (TG). The activation energies for thermal degradation of the nanocomposites were calculated from their TG data by Flynn-Wall-Ozawa method. The G values of the nanocomposites were calculated based on molecular weights which were measured by means of gel permeation chromatography before and after the gamma irradiation. The Ea and molecular weight results showed that addition of zeolite to the PLA affected the radiation resistance of the polymer. [ABSTRACT FROM AUTHOR]

During daily training, in-site firefighting and emergency rescue, firefighters often encountered multiple exposures to various thermal hazards. In this study, the tensile strengths of three typical fabrics used in firefighters’ protective clothing after exposure to multiple radiations were investigated. Radiant heat flux of 21 kW/m2was simulated by a radiant protective performance tester. Totally 12 scenarios with different exposure frequencies and durations were selected. The results showed that the tensile strength of fabric decreased after different radiation exposures. The exposure frequency, individual duration and cumulative exposure duration had impact on the tensile strength. The tensile strength decreased with the increasing of exposure frequency with the same individual duration. While keeping the same cumulative exposure duration, the longer individual exposure duration resulted in lower tensile strength. Empirical equations were developed to predict the lifetime of firefighters’ protective clothing. It can be concluded that the effects of radiation exposure frequency and individual duration on the tensile strength of firefighters’ protective clothing should be considered during protective clothing selection and maintenance. [ABSTRACT FROM AUTHOR]

In this study, the kinetics and mechanisms of thermal degradation of Poly Vinyl Chloride (PVC) composites reinforced with class-F fly ash are studied experimentally and numerically using Flynn-Wall model. The addition of fly ash to the polymer matrix results in a decrease in the primary degradation temperature and an increase in the secondary degradation temperature. The metal oxides in the fly ash act as acid absorbers, which results in the destabilization of PVC during its dehydrochlorination process. However, they also react with the chlorine free radicals, which prevents the formation of HCl during degradation. In addition, it is observed that calcium and iron oxides, present in fly ash, are more reactive to the chlorine radicals rather than the silicon and aluminum oxides. The effect of fly ash chemical composition on the degradation of PVC composites was studied by comparing the thermal properties of composites containing two different classes of fly ashes, class-F and class-C, at similar levels. Thermal stability of the composites is found to be dependent on the chemical composition of fly ash. Higher dehydrochlorination rate is observed in the case of composites filled with class-F fly ash than those reinforced with class-C fly ash. [ABSTRACT FROM AUTHOR]

Three lanthanide complexes (La(III), Er(III), and Yb(III)) derived from ferrocene-based Schiff base ligand (HL) were synthesized from condensation of 2-aminophenol with 2-acetylferrocene. The ligand and metal complexes were characterized based on elemental analyses, IR, 1H NMR, molar conductance, SEM and thermal analyses (TG, DTG). The molar conductance revealed that all the metal chelates were electrolytes having the general composition [M(L)(Cl)(H2O)3]Cl·4H2O. HL and its complexes were screened for their antibacterial and antifungal activity by agar diffusion method. The results of these studies showed that the metal complexes are more effective antibacterial and antifungal agents as compared with the free ligand. The anticancer activity was screened against human breast cancer cell line (MCF-7). Results indicated that metal complexes showed an increased cytotoxicity in proliferation to cell lines as compared to free ligand. Molecular docking studies were performed to identify the binding orientation or conformation of a complex in the active site of the protein. HL and its complexes were docked with crystal structure of DDB1 of breast cancer, crystal structure of HCV, RNA-dependent RNA polymerase, receptors of HBV core protein, crystal structure of the Fab fragment of anti-HAV. [ABSTRACT FROM AUTHOR]

Poly(imido-ester-amides) (PIEAs) derived from three new asymmetric dicarboxylic acids containing an imide and ester groups and an aminoacidic moiety (glycine, L-alanine or L-valine) and a wholly aromatic silicon-containing diamine were synthesized according to the Yamazaki method. PIEAs were characterized by spectroscopic methods including 29Si NMR and elemental analysis, and the results were in agreement with the proposed structures. The thermal properties, glass transition temperature (Tg) and thermal decomposition temperature (TDT), were determined and the results showed that both parameters decreased when the aliphatic side chain provides by the amino acids increased, due to the higher free volume between the chains, which minimizes the interactions between them. Two of the PIEAs showed transparency according to the UV-vis spectra, due to that the side chains act as chain spacers, in front of PIEA-a including glycine as aminoacidic moiety, without side aliphatic group, which did not show transparence. [ABSTRACT FROM AUTHOR]

A composite material was prepared using terpolymer and activated charcoal. The material was spectrally characterized, and the morphology and thermal stability were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), respectively. From the metal ion sorption results, it was found that the composite material had significantly removed the selected metal ions from the aqueous solution. This may be due to the highly porous nature and the larger specific surface area of the composite. The results were well fitted with the Langmuir isotherm and follow the first-order kinetics. The thermal degradation kinetics and thermodynamic parameters were also calculated from thermogravimetric data and reported. [ABSTRACT FROM AUTHOR]

In research for materials that can be applied in processing heavy oil (petroleum), this work proposes to synthesize mesoporous heterogeneous catalysts, type SBA-15, with the addition of cerium metal and aluminum. These catalysts were characterized by X-ray diffraction, scanning electron micrographs coupled to energy dispersive spectrometry, spectroscopy in the infrared region by Fourier transform, N2adsorption and desorption and thermal analysis-thermogravimetry. Thermal tests were performed to evaluate the thermal and catalytic degradation process with a sample of heavy oil (°API = 14). Through the non-isothermal kinetic model of Ozawa Flynn Wall (OFW) some parameters for determining the apparent activation energy of decomposition were obtained. The petroleum with 12% of Ce5Al50SBA-15 showed a catalytic activity for this material. It has been seen that there was a decrease in the Ea inmodel freeof the order from 89.0 to 104.9 kJ mol−1in α = 50% ± 10%, and it was repeated from the first percentage until the last showing performance of Ce5Al50SBA-15 as a catalyst. [ABSTRACT FROM PUBLISHER]

This article reports on the morphology, interfacial interaction, thermal stability, and thermal degradation kinetics of polycarbonate (PC)/mesoporous silica (MCM-41) composites with various MCM-41 contents, prepared by melt compounding. The composites with low filler loadings (<0.3 wt%) maintained their transparency because of the well dispersed MCM-41 particles, but at higher filler loadings the composites lost their transparency due to the presence of agglomerates. The presence of agglomerates decreased the thermal stability of PC due to the reduced effectiveness of the particles to immobilize the polymer chains, free radicals, and volatile degradation products. [ABSTRACT FROM AUTHOR]

The free chlorine present in water which is used as a disinfectant is reported to reduce the life of the polymeric material. The objective of this work is to study the influence of chlorine concentration on low-density polyethylene (LDPE) and blends of LDPE with ethylene butene copolymer (EBC) and ethylene propylene diene terpolymer (EPDM). The LDPE blend with EBC and EPDM were tested with water containing 50, 500, and 5000 ppm chlorine under static condition for 500 h at 25 and 80 °C. It has been seen that at 5000 ppm chlorine concentration, the mechanical properties of LDPE, LDPE/EBC blend, and LDPE/EPDM blend changed drastically and a significant reduction in the elongation at break was found for LDPE, LDPE/EBC, and LDPE/EPDM blend. LDPE/EPDM shows stable modulus value for 5000 ppm as 80 °C. Chemical changes in the aged sample were studied by Fourier transform infrared spectroscopy (FTIR) where an increase in the O–H and C=O peaks were observed. The thermal characteristics of LDPE, LDPE/EBC blend, and LDPE/EPDM blends were investigated using DSC and TGA which shows that the melting temperature and crystalline melt temperature remains unchanged while percent crystallinity increases slightly. Scanning electron microscope showed that there was the formation of microcracks and cavities on the fracture surface of LDPE, LDPE/EBC blend, and LDPE/EPDM blend after exposure to a higher concentration of chlorine indicative of degradation. Furthermore, the Chlorine resistance of LDPE/EPDM blend at 5000 ppm chlorine concentration is much higher than that of pristine LDPE. [ABSTRACT FROM PUBLISHER]

The formation of dihydroactinidiolide by thermal degradation of β-carotene was studied. A comparison of yields of dihydroactinidiolide in commercial β-carotene and β-carotene derived from crude palm oil was investigated. Thermal degradation of commercial β-carotene promoted the formation of dihydroactinidiolide with the highest yield, 61.21%. Thermal degradation of recovered β-carotene yielded 29.23% of dihydroactinidiolide. The lower recovery of β-carotene was due to the mixture of compounds in the extract. Further investigation indicated some other useful aroma compounds formed from this thermal degradation were β-ionone, 3-oxo-β-ionone, and β-cyclocitral.The outcome provided wide opportunities in utilizing crude palm oil as natural source of β-carotene to produce aroma compound. [ABSTRACT FROM PUBLISHER]

Dracocephalum kotschyiessential oils obtained by hydrodistillation (HD), microwave-assisted hydrodistillation (MAHD), and solvent-free microwave extraction (SFME) were investigated by GC-FID (Gas Chromatography-Flame Ionization Detector) and GC-MS (Gas Chromatography-Mass Spectrometry). The percentage of oxygenated compounds was significantly increased from 62.52% in HD to 76.47% in MAHD, and 84.52% in SFME. Conversely, the monoterpene hydrocarbons were decreased from 30.84% in HD to 13.71% in MAHD, and 5.85% in SFME. The main compound in the essential oil obtained by HD is limonene, which accounted for more than 30% of the oil, while the percentage of this compound was reduced to 9.52% in MAHD, and 5.60% in SFME. The percents of other oxygenated compounds such as neral, geranial, geraniol, geranyl acetate, α-terpineol,trans-verbenol, carvon, andtrans-carveol were noticeably higher in microwave methods than those present in HD method. In aqueous medium, linear oxygenated monoterpenes may be converted to a monocyclic terpinyl cation, which it could lose a proton to give limonene. The main biosynthetic pathway of these compounds, as well as a possible route of their conversion into limonene, due to prolonged heating in the HD method, was proposed. The antimicrobial activity ofD. kotschyiessential oils against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was evaluated by broth micro-dilution susceptibility manner. The most sensitive bacteria to these oils was found to beS. aureuswith the lowest minimum inhibitory concentration value of 2 mg mL−1for MAHD and SFME specimens. The results indicated that oils obtained by microwave methods were more active againstS. aureus. [ABSTRACT FROM AUTHOR]

Homopolymerization of chloro-substitutedN-phenyl maleimide monomer atortho N-OCPMI,meta N-MCPMI, andpara N-PCPMI was performed at 70°C in DMF using benzoyl peroxide as a free radical initiator. The average molecular weight of all homopolymers, namely, H-OCPMI H-MCPMI and H-PCPMI by gel permeation chromatography was found to be 1,806, 2,464, and 4,542 with PDI 1.07, 1.09, and 1.11. The controlled poly dispersity index by conventional free radical polymerization is achieved. The thermal analyses reveal that the initial decomposition temperatures for all types of homopolymers are close to each other. On increasing heating rates, the activation energy (ΔE ),entropy of activation (ΔS ), enthalpy of activation (ΔH ), and Gibbs free energy (ΔG) increase for all types of homopolymers. The homopolymer ofparachloro-substituted ofN-phenyl maleimide, H-PCPMI has the highest thermal stability. All the synthesized monomers and homopolymers are found to show an excellent antimicrobial activity. Activity index is also evaluated. [ABSTRACT FROM AUTHOR]